Otters' Penis Size Shrinking, Chemicals May be to Blame

Otters' reproductive organs may be suffering, according to scientists. Chemicals in waterways where they make their homes may be causing a decrease in the weight of otters' penis bones.

The study examined hundreds of dead otters in a post-mortem laboratory. They tested to see if existing traces of Persistent Organic Pollutants (POPs) in rivers were having an effect on the otters' health. The examination was crucial for scientists since these same chemicals helped cause a drastic decline of the otter population in England during the 1970s. Since then, many of the contaminants that plagued the otters, including organochlorine pesticides, have been banned.

These old chemicals, though, didn't seem to be causing the decrease in penis weight. Instead, it's possible that newer, modern contaminants could be causing the abnormalities. In particular, previous studies have linked Endocrine Disrupting Chemicals (EDCs) to changes in animal's reproductive organs, including male penis size. These chemicals can affect animals' hormone systems since they can interfere with the production, release, transport, metabolism, binding, action or elimination of the natural hormones in the body that are responsible for the regulation of developmental processes.

While the scientists weren't able to make a link between any of the older chemicals and the current plight of otters, they were able to see that something was affecting them. The study actually raises concerns about the feminization of male animals. In addition to the reduced penis bone weight, researchers found an increase in undescended testicles in male otters, and cysts on sperm-carrying tubes. Previous studies in the UK have linked POPs with male fish producing eggs in their testes and female egg-yolk protein.

In an interview with WalesOnline, Gwynne Lyons, one of the researchers involved in the study, said, "These findings highlight that it is time to end the complacency about the effects of pollutants on male reproductive health, particularly as some of the effects reported in otters may be caused by the same EDCs that are suspected to contribute to the declining trends in men's reproductive health and cause testicular cancer, undescended testes and low sperm count."

Scientists plan to conduct future research on the EDCs present in both the otters and their habitat in order to find a link between the chemicals and the current abnormalities found in the male otters. The otters could, in fact, act as an indicator species that could prove to be a warning sign for all mammals.